Disagreement over the legitimacy of direct sterilization continues within Catholic moral debate, with painful and at times confusing ramifications for Catholic healthcare systems. This paper argues that the medical profession should be construed as a key moral authority in this debate, on two grounds. First, the recent revival of neo-Aristotelianism in moral philosophy as applied to medical ethics has brought out the inherently moral dimensions of the history and current practice of medicine. Second, this recognition can be linked to Catholic morality through Vatican II's affirmation of the legitimate autonomy of culture, including the sciences. A partial precedent for understanding the moral authority of medicine can be found in the recent history of Catholic medical morality, and we further argue that a full contemporary recognition of that authority would weigh against an absolute prohibition of direct sterilizations. Institutionally, we propose the allowance of direct sterilizations in cases where the clinically perceived biomedical good of the patient is at stake.